Only comment I have is about side walls and heat.
The Load F tires will have significantly stiffer sidewalls than the E.
When aired down to a similar contact patch, the F will require a lower pressure, and will generate heat faster.
So keep an eye on the sidewalls, and tire temps, regardless of how low you drop the PSI.
Keeping an eye on tire temps alone will help you figure out just how fast you can go at the low PSI.
Personally, when aired down with my rather heavy setup, I keep it under 35mph, all the while keeping an eye on tire temp data.